The present invention relates to an injection apparatus particularly suitable for injecting starting fluid into the cylinders of an internal combustion engine, and more particularly to such an apparatus operated by the on-board compressed air system of a motor vehicle.
It is a common practice for internal combustion engines to be left running for long periods because the operator is not confident that the engine can be restarted with the compressed air or battery charge that is available. If an engine having an air starter is unable to start, a compressor must be brought to the engine, often at great expense. On the other hand, leaving the engine running consumes added fuel and contributes to air polution.
An internal combustion engine can be started more easily and with greater confidence if a charge of starting fluid, such as ether, preferably a combination of ether and a lubricant, is injected into the cylinders along with the regular fuel supply. Starting fluid injectors have proven particularly suitable for use with large diesel-powered vehicles since a diesel engine is not started and self-sustaining until it is able to maintain the minimum internal temperature required to cause combustion upon compression of the air-fuel mixture.
Various injector devices have been attached to engines that provide a pressurized supply of starting fluid and include a valve that permits a charge to be injected at the appropriate time. Some such devices allow the valve to be manually operated at will by a remote cable control. A more sophisticated, electrically operated device, described in this inventor's U.S. Pat. No. 3,620,424, issued on Nov. 16, 1971, provides for automatic injection of a predetermined quantity of starting fluid when the engine's starter motor is actuated.
The automatic injector referred to above utilizes a solenoid to operate two valves in sequence whenever the starter motor is energized. A first valve permits starting fluid to escape from a pressurized tank or reservoir into a resilient metering chamber. When the injector is actuated, a second valve permits the predetermined quantity of fluid contained by the metering chamber to be expelled through a starting fluid delivery conduit into the engine. This device insures that a measured quantity of starting fluid is injected each time the engine is started. Since it operation is automatic, it can be arranged to prevent the injection of starting fluid after the engine has been warmed up, thereby avoiding engine damage that could otherwise result.
Vehicles that utilize starting fluid injectors usually have on-board compressed air systems to operate air starters, brakes, horns and other accessory equipment. Copending application Ser. No. 823,398, now U.S. Pat. No. 4,166,441, issued 9/4/79, describes an injector that is powered by compressed air taken from the starter motor system. Many users prefer this arrangement to the use of electrical power for the injector. Some users are, however, hesitant to connect the injector in such a manner that it removes air from the highly sensitive starter motor circuit. Moreover, there are numerous vehicles that are not compatible with that arrangement since they have electric starters rather than air starters.
An alternative to the above approach is to connect the injector so that it is powered by air from a different compressed air circuit of the vehicle, such as the brake circuit. This arrangement is, however, objectionable since the on-board air systems for starter motors and brakes are usually separate. Thus there are circumstances in which starter air is available to start the engine and recharge the brake circuit, but the injector would be inoperative.
Another problem that arises when the injector is connected to the brake circuit of a vehicle equipped with an air starter is that of synchronizing the injector with the starter.